The instant invention is directed generally to entertainment devices which are adapted to be thrown into the air to produce a "flying" effect, and specifically to a boomerang with improved operational and flight characteristics.
The term "boomerang" is sometimes used to encompass all manner of "flying" devices; however, it should be noted here that the proper definition, and the one to be used herein, includes a narrower class of articles. More specifically, a boomerang is an aerodynamic device which, when thrown with an initial trajectory which is largely parallel to the ground describes a generally circular flight path and returns to the thrower. Devices which, when thrown upwardly at an angle "slide" back to the thrower, such as the common "Frisbee" are not boomerangs.
Referring to FIG. 1, a three dimensional picture of a returning throw of a true boomerang can be seen. An imaginery cylinder of vertical lines is added to clarify the orientation of the boomerang 20 (shown as a disc). From this it can be seen that there are three basic motions which the boomerang 20 performs during flight. First, it moves forward through the air while spinning end over end. Secondly, the boomerang makes a sweeping left turn around a roughly circular path defined generally by the periphery of the cylinder 10. Thirdly, the boomerang "lays down" during flight, i.e., the angle of the disc changes from nearly vertical to horizontal. A successful boomerang must have these three motions in proper balance.
The invention to be disclosed is limited to multi-arm devices, i.e., devices with three or more arms, so the remaining discussion will be directed to the characteristics of such devices. Throughout this disclosure, right-handed boomerangs are described, but it should be understood that the invention may be applied to left-handed boomerangs as well. In construction, a left-handed boomerang is a mirror image of a right-handed boomerang. In flight, a left-handed boomerang circles to the right instead of to the left.
Normally, the objective of flight modification is accomplished by tailoring the lay-down motion to match the turing motion. A boomerang which lays down too rapidly or too slowly cannot produce a good flight. For boomerangs with more than two arms, the conventional means of controlling lay-down is to bend the arms up or down to create positive or negative dihedral, respectively. FIG. 2A shows a boomerang 20 with positive dihedral. The flat side of boomerang 20 is down, resting on surface 21. FIG. 2B shows negative dihedral in boomerang 20 with its flat side down toward surface 21.
As will be understood shortly, the invention disclosed herein includes a novel control ring which eliminates the need for dihedral in multi-arm boomerangs, thus eliminating the difficulties associated with the proper balancing thereof with the turning motion of a specific boomerang. Also, the novel control concepts disclosed permit the construction of a boomerang of flexible materials--heretofore impossible because of the requirement for the inclusion of dihedral bending.